The present disclosure relates to toners and processes useful in providing toners suitable for electrophotographic apparatuses, including apparatuses such as digital, image-on-image, and similar apparatuses. In particular, the disclosure relates to emulsion aggregate toner compositions that use two different emulsion aggregation (EA) technologies. Namely, the present embodiments provide an emulsion aggregation toner that comprises a base resin composed of both styrene-acrylate and polyester resins. These embodiments comprise polyaluminum chloride (PAC) instead of the more commonly used aluminum sulfate as the flocculant or aggregating agent. Toners made in this manner exhibit improved surface morphology and achieved improved toner blocking and percent heat cohesion, particularly for black toner. Further, such hybrid emulsion aggregation toner compositions are lower in cost but still maintain desirable developer properties like low minimum fusing temperature (MFT) and lower dielectric loss.
Numerous processes are within the purview of those skilled in the art for the preparation of toners. Emulsion aggregation is one such method. These toners are within the purview of those skilled in the art and toners may be formed by aggregating a colorant with a latex polymer formed by emulsion polymerization. For example, U.S. Pat. No. 5,853,943, the disclosure of which is hereby incorporated by reference in its entirety, is directed to a semi-continuous emulsion polymerization process for preparing a latex by first forming a seed polymer. Other examples of emulsion/aggregation/coalescing processes for the preparation of toners are illustrated in U.S. Pat. Nos. 5,403,693, 5,418,108, 5,364,729, and 5,346,797, the disclosures of each of which are hereby incorporated by reference in their entirety. Other processes are disclosed in U.S. Pat. Nos. 5,527,658, 5,585,215, 5,650,255, 5,650,256 and 5,501,935, the disclosures of each of which are hereby incorporated by reference in their entirety.
Electrophotography, which is a method for visualizing image information by forming an electrostatic latent image, is currently employed in various fields. The term “electrostatographic” is generally used interchangeably with the term “electrophotographic.” In general, electrophotography comprises the formation of an electrostatic latent image on a photoreceptor, followed by development of the image with a developer containing a toner, and subsequent transfer of the image onto a transfer material such as paper or a sheet, and fixing the image on the transfer material by utilizing heat, a solvent, pressure and/or the like to obtain a permanent image.
Emulsion aggregation toners may comprise various resins for use in forming the latex. One type of emulsion aggregation toner provides high gloss and uses styrene-acrylate, a lower costing resin. Another type of emulsion aggregation toner provides better fusing performance (e.g., lower Minimum Fix Temperature (MFT) of about 20° C.) and uses polyesters as the base resin. However, the polyester resins used are high in cost. Thus, the present embodiments seek to form a hybrid emulsion aggregation toner that combines the advantages from both types of toners. However, it was discovered that toners with styrene-acrylate latexes do not melt at the same temperature during the toner process as the polyester toners, thus leading to variation in the surface morphology in a hybrid of the two toner types (more polystyrene/acrylate remains on the surface). The present embodiments replace some of the polyester resin used in the core of the lower fusing toner with some of the styrene-acrylate of the high gloss toner and includes PAC as the aggregating agent. Such a hybrid composition provides a lower costing toner that retains good fusing performance and low dielectric loss. Moreover, the PAC unexpectedly improves the surface morphology by reducing the amount of styrene-acrylate on the surface.